Rubber accelerator compositions



I Patented Feb. I

PATENTVOIFFI 1 301531 11; Aoostsm'roa COMPOSITIONS Ludwig Meuse'r,Naugatuck, Conn, assignor mesne assignments, "to United States Rubber.Co'mpany,.New'Y0rk, N. Y.,;a corporation of New'Jersey a, No Drawn: g.

Application Mala v20, 1936, SerialNo. 69,977 r izfoiaims." -(c1. I260-793) This invention relates to improvements in rubber acceleratorcompositions, and more particularly to means whereby torend-er orconvert wa-' ten-insoluble thiuram sulphide accelerators to Iproductsmore'suitable for latex compounding. It also relates toth'erubber products produced therewith,

According to the invention a substantially water insolublethiuramsulphide type *ofvulcanizalg) tion accelerator is heated, preferablyboiled, with an-alkali-met'al-salt of an acid whose salt forminganion'isa polyvalent radical capable of forming' a double saltwithsodium'andgammonium cations, until the thiuram sulphide dissolves.The

15' clear solution contains the new accelerator material. It may beused. as such, concentrated, or

diluted further; Examples of such acids are.

sellenous, tellurous, and sulphurous'acid. These acids formdouble saltswithys'odium and am- I monium, and subscribe to the type Hz'XOrwhere Xis a non-oxygen member of theoxygen family of the periodictable. "I I vThe invention is illustrated by the following examples with a preferredsalt, sodium sulphite, 25. reacted with tetra alkyl thiuram sulphidesamong which the more outstanding are the-tetra-methyl thiurarndisulphide, and the tetra methyl thiuram mono-sulphide: i r

Emamplel 5-90 grams of tetra-methyl thiuram disulphide are boiled forseveral'hours, in 500 grams of a water solution containing 100 gramsofanhydrous sodium-sulphite. The liquid is then cooled'and filtere-dfreeof impurities. The chemical nature of the solution is not clearlyundeb'stood; it may be thatthe alkali salt forms a t complex salt "orsome sortof a water soluble double salt with the thiuram sulphide.v r

The solution may be used as such, as theaccelerator agent, orconcentrated, or diluted. In

40 the following test, the solution was diluted to about 1433 grams withwater. A latex composi- .tion, suitable for making a. 'surgeons glove ona former, bythe dipping and coagulation method, was compounded with 32%by weight of the liquid accelerator product based on the rubber contentof the latex composition. This is figured as giving an amount of activeaccelerator constituent equivalent i302 by weight of tetramethylthiuramdisulphide. The uncured rubber glove deposited on the former, when givena water cure at 100 C., for 15 and-30 minutes respectively; and tested,showed the following tensiles at break: 4160 lbs/sq. in. for the 15minute period, .and'3320 lbs/sq. in. for the. 30 minute period. v When asimilarglove'wasairrcured at 100 C.

for 45 and minutes respectively, the tensiles were 5060 lbs/sq. in. forthe 45. minute period, and 4920'lbs./sq. in. for the 60 minute period.

Theproportion of thiuram sulphide to the salt en? may be varied withthesalt slightly in excess, :5 or the amounts may beequal asshown bythefollowing example.

Example 2; grams of tetra methyl'thiuram monosulphide are boiledwith-500 grams ora wa-j ter solution ofIOO-grainsofsodiumgsulphite'until 10 the monosulphi-dedisappears insolution." The 'clearfsolution on cooling may betreated and usedsimilarly to the corresponding sulphide;

Films obtained'from'acre'amed latex'composition containing approximately"7% by weight 15 (based on the rubber) or the liquid accelerator ofExample 2, give good results, wherethe films are formed bydipping anddrying, as well asiwhere the films'are formedby dipping and acid coag i'lating' the latexfilmsy For a 30 minute cure'in 20 air at 100 C.', theacidrcoagulated film showed a lbs/sq. in. for the dried film v p v I rThe accelerators are stable toward thepreserva; V tive (NHz) of the1atex, donot coagulate or de'- .25 stabilize the latex, and cause noundesirable pretensile of 4255 lbs./s'q.- 111;, as compared to'5596vulcanization of the, latex after standing one week at-room temperature.The stocks also age;

and Example 2 products, obtained from concentrating by evaporatingtodryness the respective, solutions-may also be used in the vulcanizationof regular solidmilled rubbers'gas shownbylthe' following tests onmixesA and B. The partsalre 35 by weight: A correspondsto base mix PartsThe two mixes were cured at 20 pounds/sq. in; steam pressure for theunaged and oxygen aged tests, and at 5 pounds/sq. in. for the scorchtest. T represents tensiles in pounds/sq. in. at break,

' and E represents percent elongation at break, 55,

- The crystalline or dry forms of Exam e 1. 30

b3? n ot 'only'a reduction intthe usually required Table I mmorp Cure inminutes The accelerators my be used inadmixture, or

in conjunction "with other organic accelerators. Theyitare compatible;with accelerators of the pto-arylene thiaaole type, allowingthereain'o'unts of the individual accelerators, but pro vid'ijnglformore durablq products. For example, where bneghalf of the accelerator ofExample 2 is replaced by the formaldehyde-aniline derivativeofmercaptobenzothiaaole, it was found that The accelerators pot-thepresent invention may be usedas compounding ingredients for the latex,prior, to vulcanization, or the uncured rubber produ ma e utedib l mm ona 0 o h t lerat may" also be vulcanize in;latex form, The acc ltteetmay.itb .pllzwi hilllli the; add l i f er m 11.3 1 5 s i ablet q or e u redfor hef'de d final rubbenproducpjlhe term rubberhere n V liifi n'e' aouchurg suttap cha ala t yntl'ietidrubb'er rubber isomers. The latex may Ybe a natural lone or one artificially} prepared to the illustrativeleiam'ples, variations in 'prot n l n ypes r h r a ent in pert ii le i'xampl er alk li-m ta. a ts. may bef ql llt t-ss hos qta sit et; d,

2,188,980 .7 I other substituted .thiuram sulphides may be, treated'suchas the corresponding penta-methcording,to,theprccess of claim 1.

The compounded latex S, to be construed broadly-as inv ylene,morpholine, or arylated thiuram sulphides,

all of which is within the spirit of the invention Having thus describedmy inventiom what r defined by the appended claims.

claim and desire to protect by-Lettersg Patent is:

product ofreaction. v 2. A process which comprises boiling asubstantially water-insoluble thiuram' sulphide vulcanizationaccelerator with an aqueous solution at analkalimetal saltiof an acid'of the type; H230 .where, Xv is a non-oxygen member of theooxygenlfamilyofthefperiodic table and re-' coyeringthewater soluble product ofreaction; i; 3. A; process which comprises heating tetramethyl thiur'amdisulphide'with an aqueous solue 1; A process; which comprises; heatinga sub- 1 stantially' water-insoluble thiuram sulphide vul-K ,canizationaccelerator with. an aqueous solution of analkalhmetal salt of an acidof the type HzXOs where' Xis a non-oxygen member of I the; 0Xygen familyof the periodic table, until the sulphide substantiallycompletelydissolves in said-solution,-and recovering the water solublel5 tion of an alkali-metalsulphite until the disu1- phide dissolves inthe solution, and cooling and recovering'the water soluble product ofreaction. 1

4.Atproces's which comprises heating tetraa methyl thiuram.monosulphide' with an aqueous solution ofa a'n. alkali-metal sulphiteuntil the-"f. monosulfide; dissolvesin the solution ancl cooling Jandrecoye'ring the water soluble product of re- 5. A vulcanizationaccelerator 6; A vulcanization accelerator obtained according to'th'eprocess of -c1aim 2.

7. A vulcanization acceleratorf obtained a r :1 c 49 obtained ao,-'

cordingi to the process of claimi3 81A vulcanization accelerator cordingto the process of claimjl,

obtained ac- 9 A latex composition containing the water' process ofclaim 3." v A I V 10. A later; composition containing the Water.

solublefproduct of reactionf resulting from the z soluble product of.reaction resulting iromfthe A process of claim 4. a

.1 A pro e sww ich ompri esu caniz ne,rub-f her in the presence of thewater solu lc. p duct; of eac i n su tin f om th ocess Iof c aimsfit12,; A processwhich comprises vuloanizing'rubr eryiny em esence o th Wte oluble p odu tteaqt qn resultin f om the proce of im .4.-

I'L DWIG MEUs R.,,

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